1/8th Scale U-95 Hydro.

[785boats]

Our Club is starting up a 1/8th Scale Hydro Class next year, so I thought I'd build the U-95. A fascinating boat with a fascinating story. I built one many years ago powered by a Profi .60 Nitro engine. It was a fast, stable hull, so I thought it should run well as an Electric. The last one was totaly scratch built, but I'm older & lazy now so I bought a kit from ML Boatworks & the cowlings from R/C Boat Company. Both excellent products & service.

The framing kit went together perfectly. Did that last week. After adding the stringers & sanding to shape I added the bottom skin of the main tub last night while my youngest boy's 18th birthday party was happening.
There's a bit of a drop down section in the middle of the tub at the front. I'd be interested to know what the theory is behind it if anyone knows.
I employed my usual method of using cans of drink for weights & squares to hold the bulkheads & frames while the epoxy sets, & then weights to hold the skin down while the epoxy sets.
Here's a few pics of the story so far.

[785boats]

Here's the rest. The thread would only allow me to upload 5 photos in the first post.

[nobbiworld]

Hey Paul, well done. Will be a lot of fun. I have a Dumas Circus Circus hydro in eighth scale waiting for this. See you next Sunday. Steve

[785boats]

Thanks Steve. I'll de there for sure.
I forgot to post a couple of images of the full size boat so here they are. This is what it should look like when it's finished.
U-95_1974.jpghydroset-u95.JPG

[siberianhusky]

Very cool! Almost did this one in 1/12 to run on spec power, you're right cool boat that was ahead of it's time.
I ended up doing a Pay N Pak turbine. Took the easy way out, much simpler cowling to build on the Pak. Runs great on a UL-1 motor, just shy of 30" long.
Might have to do this one in 1/10, was looking over the list of framing kits a few hours ago. LOL just dreaming, at the moment I have a backlog of unfinished boats. Winter is for building them, summer is for runnin' & repairin' them.

[JimClark]

Nice Choice that is a great looking hull

[tryinotocrash]

I believe the "drop down" is to help it get up on step better and faster. Nice work so far.

[JimClark]

My guess is clearance for batteries

[785boats]

A cool looking boat indeed Siberianhusky. I too have a few unfinished projects that should have been completed first. But here in sunny Queensland there is no winter. It's boating 52 weeks a year. So time for building is a bit limited.

Jim.
I thought you'd appreciate this one. The drop down certainly allows the batteries to fit more easily, & further forward too.

tryinotocrash
Getting up on the plane faster is more than likely the case with the original boat.

Cheers.
Paul.

[785boats]

Well, I've glued on the bottom & side skins of the sponsons & the side skins of the tub.
Now to seal the inside, then add the foam.
m_15.jpgm_16.jpgm_18.jpgm_19.jpgm_17.jpg

[Scott T]

Looking good Paul!

[785boats]

Thanks Scott.
Well I've sealed the insides & added the foam. I only put in about 3/4" in the bottom of each section to allow it to grow. After a few hours I pierced each section with a pencil a few times to allow air to get at the foam inside to make sure it was fully cured & wouldn't grow again in the future. It was till a bit moist & sticky in the centre of most of the sections. In some places it then grew out of the pencil holes. Then I cut off the excess above the deck line.
Yesterday (as you saw Scott) while at our clubs race day the hull spent the day sitting on the roof of my car 'baking' in the sun to encourage any more growth. But nothing happened. I pierced the sections again with a pencil & every thing was crisp & dry on the insides of all the sections. There's a few places where the foam didn't grow all the way up to the deck line, so I'll add a bit more there, sand it all to shape & then add the decks.
Here's a couple of pics. The first couple are when it was a bout half expanded, & the last one is with the piercings & the tops cut off.

m_21.jpgm_22.jpgm_23.jpg

[cybercrxt]

Looking really good so far! Glad you like the kit. One thing I might suggest is to cut out some of that foam towards the rear of the hull. The weight of it may make it that much harder to get your balance where you want it.

The center pan on the kits is really something I add to help out the FE guys as it gives you extra depth for the batteries we run. Another benefit is the lower angle you have on the bottom pan, the less likely a blowoff will happen. I strive to make 0 degrees on the hulls as much as possible, but certain kits don't allow it. Some of my older designs have more angle too as I just have not had the time to update them, but only a few are left with that issue. Not sure if the U-95 has been majorly modified to be honest. I will have to look at my plans! Mike

[785boats]

Thanks for you insight on the drop section of the centre pan Mike. Much appreciated.
I've laid out the motor & batteries,ESC & some hardware in the hull & it will be tail heavy especially when I add the wing & fins so I'm going to be adding weight anyway. That foam is as light as a feather & I don't think it will account for much. Due to the rules here in OZ, we can't run 2P packs. So it's 1P only. I'll be running it on 8s with this motor

http://shop.rcboatbitz.com.au/index.php?main_page=product_info&cPath=47_45&products_id=782

But I would appreciate it if you could advise me as to where the best COG should be, in relation to the rear of the sponsons.
Cheers.
Paul.

[cybercrxt]

Paul, You are going to find most scales need the CoG around 1-2" behind the sponson heal. Now as I start to incorporate my sport hydro design into future scale kits, that number will be 2-3" behind due to ever increasing stability in what we are finding out with those hulls. Just remember, even if the foam only weights an ounce or so, the counterbalance to counteract that extra weight makes you add a LOT more to the front of the hull to bring it back into check. I use to think it was not a big deal till I really started seeing what the numbers came out to be! Hope this helps, Mike